1. Field of Invention
The invention relates to a multichannel magnetic transducer structure with improved cross talk rejection between adjacent channels.
2. Description of the Prior Art
Multichannel transducers are generally known to employ interchannel electromagnetic shielding to reduce cross talk between adjacent channels. While these shields are reasonably effective in reducing cross talk due to leakage fields originating in the inner regions of the transducer structure, such as coils or rear gaps, they do not eliminate cross talk entirely, as well known. The conventional interchannel shields do not extend above the transducer front end surface and consequently, they are virtually ineffective for reducing cross talk caused by surface leakage fields originating, for example, from the transducing gap or from outer ends of magnetic poles of the multichannel transducer. In transducers having a plurality of closely spaced transducing channels such surface leakage fields largely contribute to the overall interchannel cross talk. As it is well known, in multichannel transducers the largest proportion of cross talk is effected between adjacent channels while more distant channels have much lesser effect since the intensity of any magnetic field, including leakage fields, progressively decreases with the square of the distance.
Some prior art multichannel transducers utilize interchannel shields extending above the front end surface of the magnetic poles. These shields might slightly improve cross talk due to surface leakage fields but at the same time they greatly increase head bumps.
There are known cross talk rejection techniques where a portion of the original electric signal of a driven channel is phase-inverted and injected in the adjacent channel. Besides the disadvantage of necessary additional electronic circuitry for phase inversion, etc., the resulting cross talk rejection is largely dependent on the phase versus frequency relationship of the original signal to the inverted signal.
According to another prior art method interchannel shields are arranged asymmetrically between channels, having their opposite ends placed in close proximity of respective opposite poles pertaining to adjacent channels. The asymmetrically arranged shields introduce a magnetic flux of opposite polarity into the adjacent channels. However, this prior art technique does not reduce cross talk resulting from surface leakage flux since these asymmetrical shields do not extend above the transducer front end surface.